The PD shanks are fragile, when compared against steel M6 screws. The PDB doc
(here) states, on p.7, that the shanks can shear if torqued to more that 3.9 N-m. That's about four pounds of force at the far end of an eight inch wrench. Not nearly as much torque as is typically recommended for steel M6 screws -- about 10 N-m for Class 8.8 or 15 N-m for Class 10.9.
However, the OP clearly stated that the person with the wrench was a veteran electrical
mentor guy. I agree this one is probably just bad luck. One of the best students on our team had similar bad luck a couple of years ago.
__________________
Richard Wallace
Mentor since 2011 for FRC 3620 Average Joes (St. Joseph, Michigan)
Mentor 2002-10 for FRC 931 Perpetual Chaos (St. Louis, Missouri)
since 2003
I believe in intuition and inspiration. Imagination is more important than knowledge. For knowledge is limited, whereas imagination embraces the entire world, stimulating progress, giving birth to evolution. It is, strictly speaking, a real factor in scientific research.
(Cosmic Religion : With Other Opinions and Aphorisms (1931) by Albert Einstein, p. 97)
Don't rely on the field staff to get every ball to work with your machine....engineer a robot that makes the change not matter. - PayneTrain [more] 
27-02-2013, 14:01
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